Progress in GEM-based gaseous photomultipliers

R. Chechik, M. Balcerzyk, A. Breskin, A. Buzulutskov, G. P. Guedes, D. Mormann and B. K. Singh
Department of Particle Physics, The Weizmann Institute of Science, 76100 Rehovot, Israel


     We discuss recent progress in gas avalanche photomultipliers operating at atmospheric pressure. They comprise UV-to-visible spectral range photocathodes coupled to multi-GEM electron multipliers. The photocathodes may be either semitransparent or reflective ones, directly deposited on the first GEM surface. These detectors provide high gain, even in noble gases, due to the suppression of photon feedback. They are sensitive to single photons, have ns time resolution, and offer good localization.
    We discuss in detail operational aspects and properties of this type of detectors. Of particular interest is the operation of CsI-based multi-GEM photomultipliers in CF4. It opens new applications in Cherenkov detectors, where both the radiator and the photosensor operate in the same gas.
     The latest results on our sealed detectors for the visible spectral range, containing bialkali photocathodes and operating with noble gas mixtures, will be presented.